Laryngeal dysfunction is prominent in asthmatic women treated by inhaled corticosteroids

Abstract Background Dysphonia is a frequent comorbidity of asthma and has been suggested to be a local side effect of inhaled corticosteroids due to laryngeal candidiasis. We hypothesized that dysphonia in asthmatics was not due to laryngeal organic lesions but to laryngeal dysfunction during phonation (LDP). Objective We compared the frequency of LDP in female asthmatic patients treated with inhaled corticosteroids to female controls. Methods We compared 68 asthmatic female patients to 53 female control subjects. Pulmonary function tests were performed and the asthmatic patients classified according to the level of inhaled corticosteroids. Dysphonia was defined as a Vocal Handicap Index ≥18 or GRBAS score ≥2. All patients underwent video laryngo‐strobe examination, analyzed blindly and separately by two otolaryngologists, describing mucosal changes, LDP, or Organic lesions linked to Laryngeal Dysfunction during Phonation (OLDP). Results 66.2% of the asthmatic patients exhibited dysphonia and 11.3% of controls (p < 0.001). No laryngeal candidiasis was found, only 3 patients presented laryngeal mucosa inflammation. LDP was observed in 60.3% of asthmatic patients and 18.9% of controls (p < 0.001), and no difference was found for OLDP (11.8% vs. 13.2%). No association was made between LDP, the dosage of inhaled corticosteroid, and bronchial obstruction. Conclusions Asthmatic patients were more dysphonic than control subjects. This phenomenon was not explained by mucosal inflammation, laryngeal candidiasis or OLDP. Asthmatic patients had more LDP than controls. There was no relation between LDP, inhaled corticosteroids dosage or bronchial obstruction. These results change our view of inhaled corticosteroid side effects in female asthmatic patients.


| INTRODUCTION
Dysphonia is a disorder characterized by altered vocal quality pitch, loudness, or vocal effort that impairs communication or reduces voice-related quality of life. 1 Dysphonia has a lifetime prevalence of 29.9% and a point prevalence of 6.6% in adults aged ≤64 years. 2 Women are more frequently affected than men, with a female/male ratio of 60:40. [2][3][4] Dysphonia can be classified into two main categories: organic and functional. 5 Organic dysphonia are the consequences of aspects not related to the use of voice, with a lot of etiologies. 5 Functional dysphonia (FD) refers to a voice disturbance that occurs in the absence of structural or neurologic laryngeal pathological characteristics, and may account for 10%-40% of cases referred to multidisciplinary voice clinics. 6  an antero-posterior constriction during phonation, and abnormal mucosal waves during phonation. [7][8][9] Primary MTD involves dysphonia in the absence of current organic vocal fold pathology, whereas secondary MTD indicates dysphonia in the presence of an underlying organic condition. 10,11 The video-laryngo-stroboscopic exam has been described as the gold standard exam for visualizing LDP. 10,12 Dysphonia has been described as more frequent in asthma than healthy subjects (11.3% vs. 5.5%). 13 An uncontrolled study on asthma has estimated an association with dysphonia in 50% of cases. 14 The main hypothesis, supported by only two limited uncontrolled studies, 15,16 was that dysphonia was caused by inhaled corticosteroids by favoring candidiasis or inducing myopathic bowing of the vocal cords.
Other laryngeal pathologies as Paradoxical Vocal Fold Movement (PVFM) and chronic cough have been associated with asthma. [17][18][19] The hypothesis of a common mechanism has been proposed for PVFM, chronic cough and MTD, implicating sensory neuronal dysfunction of the larynx. 19 Indeed, they have overlapping symptomatology and they are associated with both laryngeal dysfunction and upper airway hypersensitivity. 9,20,21 We hypothesized that the increased of dysphonia in asthmatic patients was due to laryngeal dysfunction during phonation. In order to avoid bias due to sex difference it has been decided to study only women. We compared the frequency of laryngeal dysfunction during phonation between female asthmatic patients treated with inhaled corticosteroids and healthy female controls.

| Study design
We performed a monocentric comparative study at the Chest Dis-

| Participants
Two groups of subjects were selected. The asthmatic patient group including 68 asthmatic women aged 18-70 years with persistent asthma (according to GINA 2012 [Global Initiative for Asthma] guideline) 22 who had been receiving inhaled corticosteroid treatment for at least 3 months. All asthmatic patients were selected in the allergy division in the chest disease department (Strasbourg). They were all outpatients. Asthma diagnosis was based on bronchial reversibility which had to be obtained during the last 2 years before inclusion. If not, a non-specific hyperresponsiveness to methacholine had to be demonstrated (MEDIPROM FDC 88/Paris/France) and a normal chest X ray. Inhaled corticosteroid (ICS) treatment was considered low if < 500 μg per day, medium if between 500 and 1000 μg per day, and high if > 1000 μg per day (in equivalent dose of beclomethasone). Adherence to inhaled therapy was checked by the clinician. Asthma was assessed as controlled if the patient experi- The control group included 53 non-asthmatic female volunteers aged 18-70 years. Recruitment of the controls was performed among voice practitioner students, medical school students, and hospital staff outside the Chest Diseases Department. These controls had no relationship with the department or the ENT division, were subjected to the same exclusion criteria as the patient group in addition to not having asthma.

| Paraclinical tests
In the study group, prick tests to common aeroallergens were performed unless they had been performed in the past 5 years (mite, cat, dog, aspergillus, alternaria, grass, birch, ash, ragweed, and mugwort pollen; Stallergenes Lab Antony, France). Asthma control assessment was performed according to GINA 2012. 22 In the control group, only plethysmography was performed. In both groups, lung function was tested using the same plethysmograph (Vmax/VIASYS/Hoechberg/Germany).

| Phoniatric tests
Both groups were evaluated by the VHI (French version) 24 and GRBAS scale. 25 The VHI is a validated questionnaire measuring voice problems in daily life that consists of 30 items with five response levels scored 0-4. Summarizing the scores results in a total VHI score ranging from 0 to 120. A higher score corresponds to a higher degree of patient-based vocal handicap. The VHI was normal with an overall score <18. Patients with a score ≥18 were considered dysphonic.
The GRBAS system for describing vocal quality contains five well-defined parameters: overall grade of hoarseness (G), roughness (R), breathiness (B), asthenic (A), and strained quality (S) of the voice.
Dysphonia was defined by a VHI score ≥18 and/or a GRABS score ≥2.
Phonation quotient, defined by the ratio of vital capacity to maximum phonation time, was used as an indication of air consumption. 26,27 Phonation quotient has been shown higher in disordered voice. 27,28 Maximum phonation time was obtained by asking subject to sustain the vowel/a/at a comfortable pitch and intensity level as long as possible following deep inspiration. Similarly, video laryngoscopy recordings of patients and control subjects were edited by the first ENT and each recording was identified by the allocated subject number. The recordings were rendered sound free to blind the observers to dysphonic status of each subject.
The video-laryngo-stroboscopic results were analyzed blindly and separately by two experienced ENTs specialized in vocal fold pathology. If one of the two ENTs had found LDP associated with a nodule or polyp, the patient was classified as having OLDP. If both specialists found LDP without any organic lesion, the patient was classified as having LDP. If only one of the ENT had found LDP, the subject was not classified as having LDP.

| Statistical analysis
Continuous variables were described as means and standard deviation when normaly distributed or as median and interquartile range. Categorical variables were described as the proportion of each modality.   As expected, asthmatic subjects were more likely to have rhinitis, polyposis, reflux treatment and had a lower FEV1 and FEV1/FVC (Table 1). Asthmatic patients were also older and had higher BMI, than controls (Table 1).

| Dysphonia prevalence
Patients with asthma were more likely to be dysphonic than controls whatever the score used: VHI, and/or the GRBAS score (Table 2). They also exhibited higher phonation quotient and lower maximum phonation time. Given that dysphonia increases with age, and that asthmatic subjects were older than controls, we applied the Mantel-Haenszel method to take into account the effect of age in the comparison between asthmatics and controls. The result was significant (p < 0.0001, test for homogeneity: p = 0.38), with only a slight reduction (from 5.85 to 5.33) in the magnitude of the relative risk of dysphonia for asthmatics compared to controls.

| Video stroboscopic exam
All the video stroboscopic findings are presented in the Online Table S1. No laryngeal candidiasis was reported in asthmatic patients or controls. Inflammation of the laryngeal mucosa was found in only three patients with asthma. Moreover, when considering clinical features during laryngostroboscopy performed by two ENT (see Online Table S1) no major difference was found.
The phoniatric evaluation found a greater prevalence of LDP in the asthmatic population but not of OLDP (Table 3).

| Characteristics of patients with dysphonia in the asthmatic group
Asthma characteristics between the groups with and without dysphonia were not different. The asthma control assessed by GINA was not different as well as the FEV1 and FEV1/FVC. Non atopic patients experienced less dysphonia than atopic patients. (78.2% vs.

| Role of inhaled corticosteroids
In the asthmatic population, the prevalence of LDP, and OLDP in relation to the dose of inhaled corticosteroid was not significantly different ( Table 5). The prevalence of dysphonia seemed to increase with the dosage of corticosteroid without statistical significance.
Phonation quotient was higher in medium and high dosage of inhaled corticosteroid groups.
No OLDP were found in the low ICS group. LDP seemed to be more prevalent in the low ICS group than in the medium ICS group or in high ICS group, but the difference between ICS groups was not significant (p = 0.74).

| DISCUSSION
We confirmed that patients with asthma are more likely to be dysphonic than healthy controls. Among the asthmatic patients, we observed more LDP.
To carefully define dysphonia, we used composite criteria with two validated tests. The VHI has demonstrated strong internal consistency, reliability, and test-retest stability. [29][30][31] The perceptual evaluation of voice by an ENT is a good complement to the VHI, as the GRBAS scale is examiner-based. 32    diagnosis in 47% of cases. 33 The method has been used to elaborate the classification of MTD. 34 For these reasons, the lack of stroboscopic exam is a limitation in studies on dysphonia in asthmatic patients. 16,35 Multiple etiologies have been proposed to explain dysphonia in patients with asthma. Williams et al. 16  Importantly, we found that patients with asthma were more dysphonic than control subject and did not have more Organic lesions linked to Laryngeal Dysfunction during Phonation (OLDP). Laryngeal mucosal inflammation was reported in only three asthmatic patients, and no laryngeal candidiasis was found. Our results were close to those found by Park et al., 13 who performed a large cross-sectional study comparing subjective voice complaints and organic laryngeal diseases (vocal cord polyps, vocal cord nodules, or laryngitis).
In our study, patients with asthma demonstrated more LDP than control. LDP was higher in dysphonic asthmatic patients than non dysphonic. However, the difference was not significant. Larger studies specifically designed for these objective appear to be needed to confirm these first results.
Non atopic asthmatic patients experienced dysphonia more. This finding could be in accordance with other results showing that capsaicin evoked cough responses were more important in nonatopic asthmatic. 38 Indeed Vertigan et al. showed that laryngeal dysfunction is common in the cough hypersensitivity syndrome and hypothesized that it may contribute to its mechanisms. 9 Phonation quotient was increased in patients treated by medium and high dosage inhaled corticosteroids, dysphonia rate seemed to increase too. As all our asthmatic subjects were taking inhaled corticosteroid, it was not possible to determine whether these results were associated with anti-asthmatic treatment or with asthma.
However, we did not objectively measure a dose-effect relationship between LDP, inhaled corticosteroids dosage and bronchial obstruction (FEV1/FVC).
As demonstrated by this study MTD is prevalent in patients with asthma. Voice therapy, in association with patient education and vocal hygiene, has been described efficient in primary MTD. 10,39,40 More robust evidence of efficiency was found for primary MTD than dysphonia with vocal nodule, mass lesions or with unilateral vocal fold paralysis. 41 The principal strengths of this study are a rigorous definition of dysphonia with 2 validated tests and stroboscopic analysis performed blindly by 2 otolaryngolists. The limitations are: Asthmatic population was significantly older than the control population, and dysphonia increases with age. 42 However, we showed that the bias resulting from this discrepancy was very limited, and we were able to estimate an adjusted relative risk that was significantly greater than 1. Asthmatic population exhibited higher BMI than control and dysphonia has been described more prevalent in obese population. 43 Although, in our study, we did not observed a significantly higher rate of patients with a BMI >30. The video-laryngo-stroboscopic exam was realized during phonatory tasks and not connected speech. Also, eight patients with asthma used reflux treatment without medically proven reflux. These patients could have developed dysphonia secondary to undiagnosed reflux. If so, they were treated and were not symptomatic.

| CONCLUSION
Dysphonia was more frequent in asthmatic women treated by inhaled corticosteroid than a control female population and this phenomenon was not explained by mucosal inflammation, laryngeal candidiasis or OLDP. Patients with asthma had also more LDP than controls. There was no relation between LDP and inhaled cortico-

CONFLICTS OF INTEREST
This study was partly funded by ADIRAL (Association d'Aide aux Insuffisants Respiratoire d'ALsace).

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author.